Geothermal Power Plants Could Help Produce Lithium for Electric Cars

A new process aims to extract lithium from the brines used to generate electricity in a geothermal power plant

Oct 20, 2011 - David Biello - scientificamerican.com

GEOTHERMAL LITHIUM: Chemist Elizabeth Geller of Simbol Materials observes the company's process to purify lithium and extract it from the hot brine that allows geothermal power plants to produce electricity. Image: Courtesy of Simbol Materials

An industrial add-on to geothermal power plants near the Salton Sea​ in California could one day produce the lithium that is required for electric car batteries. Already, Simbol Materials, the company behind the process, has begun purifying lithium from conventional mining operations in Argentina, Chile and elsewhere for the global battery market at a demonstration facility in Brawley, Calif.

"We developed the technology and the process to take the brines coming out of geothermal powerplants' post–power production and harvest lithium, manganese, zinc and, maybe in the future, some other materials, and we convert those into usable compounds," says Simbol CEO Luka Erceg. "We're essentially leveraging the best renewable resource and co-producing strategic materials."

After geothermal power plants pump up a hot brine—water and dissolved salts from underground—and use its heat to make steam to spin a turbine and generate electricity, Simbol would borrow the still warm fluid for roughly 90 minutes. A pipeline would carry the brine through a series of processes that remove the silica in the brine (it would otherwise foul the works) and then use a series of membranes, filters and adsorption materials to extract valuable elements like lithium. The extraction method was developed at Lawrence Livermore National Laboratory, which is primarily funded by the U.S. Department of Energy. Simbol then adds water to make up for the lost material and sends it back to the geothermal power plant for re-injection underground.

The company plans to expand its initial lithium purification facility in 2012 as well as begin construction on the geothermal-tied version as an addition to such power plants being built in the region by EnergySource. Already, there are 10 geothermal power plants in the Imperial Valley. "You can produce 16,000 metric tons of lithium carbonate for every 50-megawatt geothermal power plant," Erceg notes.

As a result of re-injection, the company will not be left with the residue from traditional lithium mining. Plus, instead of relying on hard rock mining as is typical of production today, Simbol lets the hot water of the subsurface Salton Sea do the work of leaching the materials out of the rock as well as purifying them into salts—a process that involves evaporating water from lithium ponds for other producers around the world, including in the U.S.

Also, the company would not need to purchase soda ash to enable production of lithium carbonate, as is typically done today. Instead, Simbol will take advantage of waste carbon dioxide from the geothermal power plant itself to create the material. Another economic advantage of Simbol's lithium process is its location: a mere 320 kilometers from southern California's three major ports and not thousands of meters above sea level, as are the major mines in South America that provide most of the world's lithium today. It remains to be seen, however, if Simbol's product can compete with that generated by the big producers in Argentina, Australia, Chile and, in the future, Bolivia.

The Salton Sea brine contains a host of other elements, and Simbol hopes to extend the extraction process to manganese and zinc—also used in batteries and metal alloys—as well as potassium, which is a vital nutrient and fertilizer, among other applications. "This brine has got half the periodic table in it and that's a good news–bad news situation," Erceg says, noting that cesium, rubidium and silver might also be produced the same way. The company is also exploring options for using the process's waste silica—more commonly known as sand—in the cement industry.

But the 500 metric tons per year of lithium from this initial purification facility will not be going to U.S.-based battery-makers, at least not yet. Instead, the ITOCHU Corp., a Japanese partner of Simbol, will sell the purified lithium to battery-makers on the other side of the Pacific Ocean. "The initial output of this plant, we expect to go to Asia," Erceg notes. "The reality is, today, for lithium ion batteries, manufacturing still means Asia."